CN108311088A - Injecting type annular-pipe reactor and the method for preparing butyl type rubber polymer - Google Patents

Abstract

The invention discloses a jet-type loop reactor, which comprises: a loop reaction pipeline, a jet mixing device, an axial flow pump, a heat exchange device, a material inlet and a material outlet. The reactor can provide an excellent macro-mixing and micro-mixing environment for the reaction; it is also easy to realize multi-point feeding and multi-stage temperature control, which is beneficial to control product distribution.

Description

Jet loop reactor and method for preparing butyl rubber-based polymer

technical field

The invention relates to a jet loop reactor, in particular to a jet loop reactor used for the production of butyl rubber polymers.

Background technique

Butyl Rubber has been known since the 1930s, and their synthesis and properties are described by Kresge and Wang in 8KIRK-OTHMER ENCYCLOPEDIA OF CHEMICAL TECHNOLOGY, pages 934-955 (4th edition , 1993). The polymerization process of butyl rubber has the characteristics of low temperature, rapidity and large heat release, so the reactor is required to have good heat transfer, mass transfer and micro-mixing performance, otherwise the reactor will be gelled and blocked due to local reaction overheating.

At present, the butyl rubber polymerization reactors used in industry mainly include axial-flow tubular reactors and multi-layer stirred reactors.

The multi-layer stirred reactor was proposed by Russian patents RU1615935 and RU2097122. The structure is relatively simple. The reactor is equipped with a multi-blade stirrer and multiple sets of heat exchange tube bundles. The mixed material enters the main body of the reactor from the bottom of the reactor. Stir in an upward spiral. The heat of reaction is taken away by the vaporization of the ethylene liquid inside the heat exchange tube bundle. The main disadvantage of this type of reactor is that the lateral dispersion ability is relatively weak, so the tendency of gelling is greater than that of the axial flow tube type reactor, and the product quality is poor.

Axial-flow tubular reactors are divided into two types: the old type (drain tube) and the new type (central tube bundle type). Wherein the old type reactor is proposed in the former U.S. Patent US448575, and perfected in the patents US2474592 and US2999084. The reactor consists of a vertical vessel formed by closed side walls, inside which there is a relatively large diameter central guide tube, which is surrounded by many small diameter tube bundles extending downward. The liquid hydrocarbon coolant flows on the shell side, and takes away the heat of reaction by contacting the outer wall of the small diameter tube and the wall of the central guide tube for heat exchange. At the top of the reactor, a part of the polymer slurry is discharged, and the other part is circulated back to the bottom of the reactor through the peripheral tube bundle of the draft tube, and the axial flow pump installed at the bottom is pumped up to the draft tube. The heat exchange at the initial stage of the reaction and the uniform distribution of the reactant concentration are realized by circulating the slurry and the back mixing of the fresh material. Among them, the patent US2999084 mentions that, in commercial practice, aggregation and fouling are the main restrictive factors for increasing the yield of butyl rubber. Fouling reduces the heat transfer capacity of the reactor, and in severe cases, it needs to be shut down for cleaning. It is the main reason for the running reactor to be operated at an interval of about 10 to 90 hours. It usually takes 10 hours to clean the reactor before resuming the polymerization reaction. to 20 hours.

Therefore, Exxon has improved the reactor and developed a new type of double-tube axial flow column-tube reactor. This reactor is described in patent US5417930. In terms of structure, the new reactor changes the original guide tube with a large middle diameter (diameter 60.0cm) into a central tube bundle with a small diameter (the most suitable diameter is about 76.2mm) to enhance heat exchange; at the same time, the bottom of the reactor uses a diffuser And the mixing pump system enables the slurry to circulate at a higher speed, and the circulation rate is 40% to 50% higher than that of the old reactor. Due to the high circulation rate, the viscosity of the slurry decreases, the tendency of gelling is further reduced and the heat transfer coefficient is improved. However, the structure of the new double-pass axial-flow tubular reactor is more complicated, the processing requirements are high, and the pressure drop is much higher than the old one. In addition, when the initiator solution and the monomer solution of the axial-flow tubular reactor are in contact, they are mixed by traditional mechanical agitation. The microscopic mixing ability is poor, and it is difficult to match the fast polymerization rate of butyl rubber. Clumping.

These considerations imply a need for a reactor with better micro-mixing properties and a simpler structure to reduce the tendency of the reactor to gum up and increase the run cycle and butyl rubber yield.

On the other hand, we also hope that the new reactor can produce higher quality products. It is well known that the physical properties and processability of polymers mainly depend on molecular weight and molecular weight distribution. It has been found that butyl rubber with a wide molecular weight distribution has excellent mixing characteristics in internal mixers, and has good cold flow properties, higher green rubber strength, and easy molding; but it has serious defects in shrinkage properties, stress relaxation The speed is reduced, and it is easy to deform and crack. A compromise is therefore required to properly control the molecular weight distribution of butyl rubber.

In the patent US5071913, it is mentioned that polymers or polymer components with great differences but definite molecular weights can be blended together to form a specific molecular weight distribution method. These are polymers and blends of polymers that combine the high green strength contributed by the higher molecular weight butyl polymer with the lower viscosity and faster stress relaxation contributed by the lower molecular weight butyl polymer. The patent also mentions that this blending effect can be completed directly in the synthesis process, that is, the products of two or more parallel or series polymerization reactors are mixed together, or two or more reactions in the same reactor are mixed together. The products polymerized in the zones are mixed together within the reactor.

At present, the production of butyl rubber mostly adopts the method of simultaneous production in multiple kettles, and the method of blending products with various molecular weights outside the kettle. Due to the large differences in the residence time distribution and reaction rate of each tank, the structure of such products is relatively inhomogeneous, and it is difficult to obtain products with a specified molecular weight distribution, so as to realize the regulation of molecular weight distribution. Therefore, it is considered to carry out multi-zone mixing in the new reactor to reduce the inhomogeneity of product quality and realize the control of molecular weight distribution.

Contents of the invention

Aiming at the above-mentioned technical problems existing in the prior art, the present invention proposes a jet-type loop reactor and its usage method. The reactor obtains a uniform concentration by providing an excellent macro-mixing and micro-mixing environment for the reaction. And temperature distribution, which is beneficial to the rapid reaction of butyl rubber polymerization; it is also easy to realize multi-point feeding and multi-stage temperature control, which is beneficial to control product distribution.

The reactor is suitable for the production of polyisoolefins, especially butyl rubber-based polymers, by the slurry polymerization process in cationic polymerization under the Friedel-Crafts catalyst. The invention is also applicable to the production of other reactants for rapid slurry polymerization.

According to a first aspect of the present invention, a jet loop reactor is proposed. It includes a circular reaction pipeline, a jet mixing device, an axial flow pump, a feed inlet and a discharge outlet, wherein the circular reaction pipeline is composed of a straight pipe section and a curved pipe section, and preferably includes four or more than four vertical pipes. Straight pipe, four or more than four bent pipes are connected end to end. There are multiple jackets for heat exchange on the circular reaction pipeline, and different temperature control ranges can be set at different parts of the pipeline. There are one or more axial flow pumps in the circular reaction pipeline. The jet mixing device has three interfaces, the main fluid inlet, the injection fluid inlet, and the main fluid outlet, wherein the main fluid inlet and the main fluid outlet are respectively connected to the annular reaction pipeline.

The feed inlet can be placed at any position in the circular reaction pipeline, which can be a straight pipe section or a curved pipe section, preferably a straight pipe section. There can be one or more feeding ports. The discharge port can be arranged at the upper bend or the lower bend of the circular reaction pipeline, preferably at an angle of 15-85° to the vertical direction. There can be one or more outlets. The discharge method can be continuous or intermittent. The material inlet and outlet can be connected with pipelines or material inlet and outlet devices.

As a preferred manner, the jet mixing device is provided with a heat exchange device for adjusting the temperature of the fluid in the device.

As another preferred mode, the jet mixing device is composed of a receiving chamber, a mixing chamber and a diffusion chamber from bottom to top; the bottom of the receiving chamber has an injection fluid inlet; the mixing chamber includes a converging section and a throat; the The diffusion chamber is upwardly connected to the straight pipe section of the annular reaction pipeline through the main fluid outlet; the straight pipe section of the annular reaction pipeline is connected to the main fluid inlet of the jet mixing device. The main fluid inlet is a nozzle type, and the nozzle extends into the converging section of the mixing chamber.

As another preferred mode, there are one or more jet mixing devices in the circular reaction pipeline, and at least one feeding port is provided in front of each jet mixing device.

As another preferred mode, the diameter of the annular reaction pipeline is 1.1 to 5 times, preferably 1.1 to 3 times, the diameter of the throat of the jet mixing device.

As another preferred manner, the area ratio of the jet reactor is 1.1-25, preferably 1.2-8.

The present invention also provides two kinds of specific preferred schemes:

A kind of preferred scheme is that there are 4 straight pipe sections and 4 curved pipe sections respectively in the annular reactor, a jet mixing device is arranged, and a feed inlet is set at the straight pipe section closest to it (counter fluid flow direction), Its most recent (along the direction of fluid flow) downbend pipe section and the vertical direction are at an angle of 45° to upwardly set a discharge port. The area ratio of the jet reaction device is preferably 1.0 to 4, and the throat distance of the jet reaction device is preferably 0.5 to 0.7 times the diameter of the throat; the length of the throat is preferably 5 to 7 times the diameter of the throat; the jet reaction of the jet reaction device The nozzle of the device is preferably a contracting conical shape with a simple structure, the contraction angle α is preferably 10°-30°; the half-angle of the throat inlet angle β is preferably 10-30°; the divergence angle θ is 5-8°.

Another preferred solution is that there are 8 straight pipe sections and curved pipe sections respectively in the annular reactor, and two jet mixing devices are used to properly widen the molecular weight distribution of the product to improve product performance. A feed inlet is provided on the straight pipe section closest to each jet mixing device (counter-fluid flow direction), and an angle of 45° to the vertical direction is provided on the down-bent pipe section closest to each jet mixing device (along the fluid flow direction). Each corner is provided with a discharge port facing upwards. A heat exchange jacket is arranged outside the annular reaction pipeline and the jet mixing device.

Part nouns are defined as follows in the present invention:

The jet reactor area ratio is defined as the ratio of the throat area to the nozzle outlet area.

The throat-to-mouth distance of a jet reaction device is defined as the distance between the nozzle outlet and the throat inlet.

The circulation ratio of the reactor is defined as the ratio of the output flow rate of the reactor to the circulation flow rate (the sum of the flow rate of the main fluid and the injection fluid) in the reactor.

According to the second aspect of the present invention, a kind of production method of the butyl rubber based polymer based on the above-mentioned injection loop reactor is proposed, comprising: pre-cooling the mixed liquid of the monomer mixture and the diluent to the reaction required temperature, and then inject it from the feed port in the circular reaction pipeline; pre-cool the mixture of initiator and diluent to the temperature required for the reaction, and then inject it from the initiator inlet in the jet mixing device; eject the fluid The volume flow ratio of the main fluid and the main fluid is controlled at 0.0005-0.05; the reaction temperature is controlled at -90°C--100°C; after the reaction is completed, the butyl rubber polymer is obtained by removing the diluent, washing, and drying.

A preferred method is that the composition of the monomer mixture is 90-99.5 wt% isomonoolefin and 0.5-10 wt% conjugated diene.

Another preferred method is that the flow velocity of the fluid in the annular reaction pipeline is 3-15m/s, preferably 5-12m/s; the flow velocity at the nozzle of the jet mixing device is 8-30m/s, preferably 10-25m/s.

Another preferred method is that there are multiple jet mixing devices in the reactor, and the monomers in the feeding port before each jet mixing device are isomonoolefins and conjugated dienes in different proportions.

Another preferred method is that there are multiple jet mixing devices in the reactor, and the fluid in each jet mixing device has a different temperature. More preferably: among the two jet mixing devices, the temperature of the first jet mixing device is controlled at -93 to -97°C, and the temperature of the other jet mixing device is controlled at -92 to -96°C.

The advantages of this reactor are: not only the structure is simple and easy to process, it can provide an excellent macro-mixing and micro-mixing environment for the reaction, reduce glue hanging, and improve the operation cycle; it can also produce products with an appropriate amount of wide molecular weight distribution and improve product quality.

Description of drawings

The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. In addition, the shapes and proportional dimensions of the components in the drawings are only schematic and are used to help the understanding of the present invention, and do not specifically limit the shapes and proportional dimensions of the components in the present invention. Under the enlightenment of the present invention, those skilled in the art can choose various possible shapes and proportional dimensions according to specific situations to implement the present invention.

Fig. 1 is a kind of preferred jet loop reactor sectional view provided by the present invention;

Fig. 2 is the local schematic diagram of jet mixing device;

Fig. 3 is a sectional view of another preferred jet loop reactor provided by the present invention.

Detailed ways

Fig. 1 is a cross-sectional view of a preferred jet loop reactor provided by the present invention. It includes an axial flow pump 1, a jet mixing device 2, annular reaction pipes 3, 4, feed ports A, B and a feed port C. Wherein, the circular reaction pipeline is composed of a straight pipe section 3 and a curved pipe section 4 . There are multiple jackets for heat exchange in the straight pipe section, and different temperature control ranges can be set in different parts of the straight pipe section. There are one or more axial flow pumps in the circular reaction pipeline. The jet mixing device has three interfaces, a main fluid inlet, an injection fluid inlet, and a main fluid outlet, wherein the main fluid inlet and the main fluid outlet are respectively connected to the annular reaction pipeline. A heat exchange device may preferably be provided outside the jet mixing device to adjust the temperature of the internal fluid. The feed inlet can be placed at any position in the circular reaction pipeline, which can be a straight pipe section or a curved pipe section, preferably a straight pipe section. There can be one or more feeding ports. The discharge port can be set at the upper bend or lower bend of the annular reaction pipeline, and the vertical direction is 15-85°. There can be one or more outlets. The discharge method can be continuous or intermittent. The material inlet and outlet can be connected with pipelines or material inlet and outlet devices.

The arranged jet mixing device has a structure from bottom to top in order of receiving chamber 2 ^a , mixing chamber 2 ^b and diffusing chamber 2 ^c . There is an injection fluid inlet at the bottom of the receiving chamber; the mixing chamber includes a converging section 2 ^{b, 1} and a throat pipe 2 ^{b, 2} ; the diffusion chamber is connected upwardly with the straight pipe section of the annular reaction pipeline through the main fluid outlet. The annular reaction pipeline is connected with the main fluid inlet of the jet mixing device, the main fluid inlet is a nozzle type, and the nozzle 2 ^d extends into the converging section 2 ^b,1 of the mixing chamber.

The mixture of monomer mixture and diluent is pre-cooled to the temperature required for the reaction, and then injected from the feed port A close to the bottom of the axial flow pump, mixed with the circulating slurry in the annular reaction pipeline, and then pumped by the axial flow pump 1 pressurized into a high-speed working fluid, enters the jet mixing device 2 through the nozzle 2 ^d , generates a low pressure, and entrains the mixture of the pre-cooled initiator and diluent from the injection fluid inlet into the jet reaction device 2, the two Rapid mixing and reaction occurs, and the reaction temperature is controlled within -90°C to -100°C. The volume flow ratio of the injection fluid and the main fluid is controlled at 0.0005-0.05. The rubber slurry and unreacted monomers generated by the reaction continue to enter the circular reaction pipeline 3 and 4 for circulation, the circulation flow rate is controlled at 3-15m/s, part of the mixed material overflows from the outlet C, and the residual material continues to circulate in the circular Circulate in the reaction pipes 3 and 4, and mix and exchange heat with fresh reaction materials. The mixed material flowing out from the outlet C is processed after removing the diluent, washing and drying to obtain the butyl rubber product.

Figure 2 shows the structure of the jet pump reactor. The high-speed fluid pressurized by the axial flow pump 1 enters the mixing chamber 2 ^b of the jet reaction device sequentially through the nozzle 2 ^d , where a low pressure is generated in the mixing chamber 2 ^b , and the initiator solution is drawn from the injection fluid The inlet entrains into the mixing chamber 2 ^b , where rapid mixing and reaction takes place. The rubber slurry and unreacted monomers generated by the reaction continue to flow through the diffusion chamber 2 ^c and enter the circular reaction pipe 3 and 4 for circulation.

As shown in FIG. 3 , the jet loop reactor has two jet reactors, and each jet reactor has a feed port A in front of the jet reactor. One implementation method can enter monomer solutions with different feed ratios from two feed ports to generate butyl rubber slurry, which is then mixed inside the ring-shaped reaction pipeline. Another implementation method is that the temperature of the first jet mixing device is controlled at -93 to -97°C, and the temperature of the other jet mixing device is controlled at -92 to -96°C.

Example 1

The reactor shown in Figure 1 was used for the pilot test to produce butyl rubber. Under the H ₂ O/EtAlCl ₂ initiation system, the temperature in the reactor was kept at -97°C. The inner diameter of the circular reaction pipe is 300mm, the height is 23.5m, the number of straight pipe sections is 4, and there is 1 jet reaction device. The feed solution is a monomer mixed solution of 28.04wt% isobutylene, 0.87wt% isoprene and 71.09wt% monochloromethane, which is mixed with the slurry circulated from the circular reaction pipeline after entering from the feed port. About 250. The mixed material liquid is accelerated by the axial flow pump to reach a speed of 7.5m/s, and is injected from the nozzle into the mixing chamber of the jet reactor at a speed of about 20m/s. The 0.25MPa initiation system is entrained into the jet reaction device under the action of pressure difference. The reaction monomer and the initiation system are rapidly mixed and reacted in the mixing chamber of the jet reaction device. The microscopic mixing time is about 0.002s. After the reaction, the slurry solution and unreacted monomer enter the circular reaction pipeline through the diffusion chamber. As the product overflows upward from the discharge port, the residual material continues to circulate in the circular reaction pipeline, mixing and exchanging heat with the fresh reaction material. The reactor runs continuously for 10 hours, the average conversion rate of isobutene is about 80%, and the amount of gum hanging is 30% lower than that of the traditional reactor. The energy loss of the whole reactor is about 0.19MPa. The number average molecular weight M _n of the butyl rubber product was 1.95×10 ⁵ , and the molecular weight distribution index was 3.55.

Example 2

The reactor shown in Figure 3 was used for the pilot test to produce butyl rubber. Under the H ₂ O/EtAlCl ₂ initiation system, the temperature in the reactor was kept at -97°C. The inner diameter of the circular reaction pipe is 300mm, the height is 23.5m, the number of straight pipe sections is 8, there are 2 jet reaction devices, and 2 feed ports. The feed solution in one feed inlet is a monomer mixed solution of 28.04wt% isobutylene, 0.87wt% isoprene and 71.09wt% methylene chloride, and the feed solution in another feed inlet is 28.48wt% isobutylene, 0.43wt% A monomer mixed solution of isoprene and 71.09 wt% methylene chloride. The method of Example 1 was repeated. The reactor runs continuously for 10 hours, the average conversion rate of isobutene is about 80%, and the amount of gum hanging is 32% lower than that of the traditional reactor. The energy loss of the whole reactor is about 0.40MPa. The number average molecular weight M _n of the butyl rubber product was 1.90×10 ⁵ , and the molecular weight distribution index was 3.80.

Example 3

The reactor shown in Figure 3 was used for the pilot test to produce butyl rubber. Under the initiation system of H ₂ O/EtAlCl ₂ , the temperature inside the ring reaction tube was maintained at -97°C. The inner diameter of the circular reaction pipe is 300mm, the height is 23.5m, the number of straight pipe sections is 8, and there are 2 jet reaction devices. The feed solution was a monomer mixed solution of 28.04 wt% isobutylene, 0.87 wt% isoprene and 71.09 wt% methylene chloride. The temperature of one jet reaction device was controlled at -97°C, and the temperature of the other jet reaction device was controlled at -96°C, and the method of Example 1 was repeated. The reactor runs continuously for 10 hours, the average conversion rate of isobutene is about 80%, and the amount of gum hanging is 25% lower than that of the traditional reactor. The energy loss of the whole reactor is about 0.40MPa. The number average molecular weight M _n of the butyl rubber product was 2.10×10 ⁵ , and the molecular weight distribution index was 4.30.

While the invention has been described with reference to a preferred embodiment, various modifications may be made and equivalents may be substituted for parts thereof without departing from the scope of the invention. In particular, as long as there is no structural conflict, the technical features mentioned in the various embodiments can be combined in any manner. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims (10)

1. A jet-type loop reactor, comprising annular reaction pipeline, jet mixing device, axial flow pump, feed inlet and discharge outlet, is characterized in that: The annular reaction pipeline is composed of a straight pipe section and an elbow section, and multiple jackets for heat exchange are arranged on the annular reaction pipeline; there is a jet mixing device on the annular reaction pipeline, and the jet mixing device has 3 interfaces , the main fluid inlet, the injection fluid inlet and the main fluid outlet, wherein the main fluid inlet and the main fluid outlet are respectively connected with the annular reaction pipeline. 2. The jet loop reactor according to claim 1, characterized in that: said jet mixing device has a heat exchange device outside it. 3. The jet-type loop reactor according to claim 1, characterized in that: the jet mixing device is composed of a receiving chamber, a mixing chamber and a diffusion chamber from bottom to top; the bottom of the receiving chamber has an injection fluid inlet; The mixing chamber includes a converging section and a throat; the diffusion chamber is upwardly connected to the straight pipe section of the annular reaction pipeline through the main fluid outlet; the straight pipe section of the annular reaction pipeline is connected to the main fluid inlet of the jet mixing device, and the main fluid The inlet is in the form of a nozzle, and the nozzle extends into the converging section of the mixing chamber. 4. The jet-type loop reactor according to any one of claims 1 to 3, characterized in that: there are one or more jet mixing devices in the ring-shaped reaction pipeline, and at least one feeding material is arranged before each jet mixing device mouth. 5. The jet loop reactor according to any one of claims 1 to 3, characterized in that: the diameter of the annular reaction pipeline is 1.1 to 5 times, preferably 1.1 to 3 times, the throat diameter of the jet mixing device . 6. The jet loop reactor according to any one of claims 1 to 3, characterized in that the area ratio of the jet reaction device to the jet reaction device is 1.1-25, preferably 1.2-8. 7. A method for preparing butyl rubber-based polymers in the spray-type loop reactor described in any one of claims 1 to 6, characterized in that: the mixed solution of monomer mixture and diluent is pre-cooled to the temperature required for the reaction, and then inject it from the feed port in the circular reaction pipeline; pre-cool the mixture of initiator and diluent to the temperature required for the reaction, and then inject it from the initiator inlet in the jet mixing device ; The volume flow ratio of the injection fluid and the main fluid is controlled at 0.0005 ~ 0.05; the reaction temperature is controlled at -90 ° C ~ -100 ° C; after the reaction is completed, carry out post-processing of removing diluent, washing, and drying to obtain butyl rubber polymer . 8. The method according to claim 7, characterized in that: the flow velocity of the fluid in the annular reaction pipeline is 3 to 15m/s, preferably 5 to 12m/s; the flow velocity at the nozzle of the jet mixing device is 8 to 30m/s, Preferably 10-25m/s. 9. The method according to claim 8, characterized in that: there are multiple jet mixing devices in the reactor, and the monomers in the feed inlet before each jet mixing device are isomonoolefins and conjugated diolefins in different proportions . 10. The method according to claim 9, characterized in that there are multiple jet mixing devices in the reactor, and the fluid in each jet mixing device has a different temperature.